Bundled = Derated

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Re: Bundled = Derated

All I can tell you guys that say it's not bundling is that you would be reworking a lot of circuits here in MA if you wanted to pass inspection. :D

You may all be right from an NEC position but not here. For us official NEC interpretations are not an option. If we want an official interpretation it comes from the Mass Board of Fire Prevention Regulations.

Bob

[ September 19, 2005, 02:59 PM: Message edited by: iwire ]
 
Re: Bundled = Derated

Even if this is bundling (which I don't think it is), 310.15(A)(2) exception will nullify it, since according to Dave the "bundle" is 48" in length.
 
Re: Bundled = Derated

Originally posted by ryan_618:
Even if this is bundling (which I don't think it is), 310.15(A)(2) exception will nullify it, since according to Dave the "bundle" is 48" in length.
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I can not even imagine going down that road with the local inspector. :D
 
Re: Bundled = Derated

Originally posted by iwire:
Originally posted by ryan_618:
Even if this is bundling (which I don't think it is), 310.15(A)(2) exception will nullify it, since according to Dave the "bundle" is 48" in length.
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I can not even imagine going down that road with the local inspector. :D
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But what if the local inspector is me? :D
 
Re: Bundled = Derated

Where single conductors or multiconductor cables are stacked or bundled longer than 600 mm (24 in.) without maintaining spacing and are not installed in raceways
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In the town that I inspect in, I read this as you have to maintain the space, by such means as separate holes or hangers that have space between the cables such as stack-its or the 3m furring strips, or any other method that offers a physical separation between the cables. I just don't see were cables installed, even through substantially large drilled holes, maintain space while gravity is working against them.

Jim
 
Re: Bundled = Derated

Originally posted by volt102:
...I just don't see were cables installed, even through substantially large drilled holes, maintain space while gravity is working against them...
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I'm not working against anyone! ;)
 
Re: Bundled = Derated

iwire: are you saying that in mass. you cannot run more than three romex in a hole irregardless of derating? Derating allows up to 10 cables as ".." said before the derating affects the circuit overcurrent protection, or load, at least for the smaller romex.

I find that kind of odd, since they allow unprotected SE to run into a house. Here in CA, which does not care about consistency either, it is the opposite, generally. SF is its own world and to some extent rightly so; old, old wood common wall structures with ancient wiring, any new stuff is generally strict. They pretty much burned down once.

paul
 
Re: Bundled = Derated

I wonder why, if we are talking about derating, we dont apply the adjustments for ambient temp's found at the bottom of 310.16? This may not apply in a basement but I think it very well could in an attic where the cables are ran together (or shall we say bundled). :confused:
 
Re: Bundled = Derated

Originally posted by apauling:
Derating allows up to 10 cables as ".." said before the derating affects the circuit overcurrent protection, or load, at least for the smaller romex.
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Cables or Conductors?

Jim
 
Re: Bundled = Derated

Originally posted by apauling:
iwire: are you saying that in mass. you cannot run more than three romex in a hole irregardless of derating?
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No, not at all.

What I am saying is we can only pass 9 current carrying conductors through the same hole in studs, joists etc. at lengths longer than 24".

That may be 2, 3, or 4 cables

Originally posted by apauling:
Derating allows up to 10 cables as ".." said before the derating affects the circuit overcurrent protection, or load, at least for the smaller romex.
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Actually that would be up to 9 current carrying conductors, not 10.

Originally posted by apauling:
I find that kind of odd, since they allow unprotected SE to run into a house.
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I do not see the connection.

However if I bundled the SE with other NMs I would have to derate that too. :D

One thing that may have influence here in MA is that we use a less restrictive derating table.

You can see the table we use in the back of the current NEC, it is Table B.310.11.

From 1 to 9 conductors the table we use is the same as Table 310.15(B)(2)(a) above 9 conductors and the derating is much less restrictive.

[ September 21, 2005, 03:12 PM: Message edited by: iwire ]
 
Re: Bundled = Derated

I think that everyone needs to read 334.80. It only allows for 2 nm cables.
Here I only allow 4-2 wire cables though the same hole.I also take into account if this is in an attic or exterior insulated walls.Around here their is usually a 2' nipple out of the panel plus the wires are usually ty-raped inside the panel
Paul Gretna Electrical Inspector
 
Re: Bundled = Derated

Originally posted by bassphisher:
I think that everyone needs to read 334.80. It only allows for 2 nm cables.
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How so?

334.80 Ampacity.
The ampacity of Types NM, NMC, and NMS cable shall be determined in accordance with 310.15. The ampacity shall be in accordance with the 60?C (140?F) conductor temperature rating. The 90?C (194?F) rating shall be permitted to be used for ampacity derating purposes, provided the final derated ampacity does not exceed that for a 60?C (140?F) rated conductor. The ampacity of Types NM, NMC, and NMS cable installed in cable tray shall be determined in accordance with 392.11.
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Re: Bundled = Derated

Right derate after 2-2 wire cables. And I consider the cables bundled in the panel if they are ty-raped.Plus they are all crammed into a nipple before they go through the floor.And then into an insulated exterior wall then into an attic.

[ September 21, 2005, 05:02 PM: Message edited by: bassphisher ]
 
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